Stent and method for manufacturing thereof

ABSTRACT

According to one aspect of the present disclosure, a method and technique for manufacturing a stent are disclosed. The stent is a non-metallic stent having a furled small-diameter state and an expanded large-diameter state where the stent, in the furled small-diameter state, includes a plurality of central lobes arranged at spaced-apart intervals and extending longitudinally defining a stent axis, the plurality of central lobes defining a cylindrical plane of the stent. The stent also includes at least one peripheral lobe formed on at least one of the plurality of central lobes, the peripheral lobe oriented along the cylindrical plane.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. application Ser.No. 14/860,878, entitled “Stent and Method for Manufacturing Thereof”and filed on Sep. 22, 2015, which is a continuation of U.S. applicationSer. No. 12/947,767, now U.S. Pat. No. 9,155,640, entitled “Stent andMethod for Manufacturing Thereof” and filed on Nov. 16, 2010, whichclaims the benefit of priority from U.S. Provisional Application No.61/261,486 entitled “Stent and Method for Fabrication Thereof” and filedon Nov. 16, 2009. This application claims the benefit of priority fromeach of the above applications, which are incorporated herein byreference.

BACKGROUND

Stents are used for the treatment of various types of vascularconditions. A stent can be implanted within a vessel in a smallconfiguration using a delivery catheter and then expanded to a largersize against the walls of the vessel.

BRIEF SUMMARY

According to one aspect of the present disclosure, a stent and methodand technique for manufacturing a stent are disclosed. According to oneembodiment, the stent comprises a non-metallic stent having a furledsmall-diameter state and an expanded large-diameter state. The stent, inthe furled small-diameter state, includes a plurality of central lobesarranged at spaced-apart intervals and extending longitudinally defininga stent axis, where the plurality of central lobes define a cylindricalplane of the stent. The stent also includes at least one peripheral lobeformed on at least one of the plurality of central lobes where theperipheral lobe is oriented along the cylindrical plane of the stent.

According to another embodiment, the stent includes a first plurality ofcentral lobes arranged at spaced-apart intervals and extendinglongitudinally defining a stent axis, where the first plurality ofcentral lobes is formed by an element extending in a coiled manner froma proximal end of the stent to a distal end of the stent. The stent alsoincludes a second plurality of central lobes arranged at spaced-apartintervals and extending longitudinally in the direction of the stentaxis, where the second plurality of lobes is formed by the elementreturning from the distal end to the proximal end in a coiled manner.The stent further includes at least one peripheral lobe formed on atleast one of the first plurality of central lobes and on at least one ofthe second plurality of central lobes, each peripheral lobe extendingradially inward toward an internal area of the stent.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a more complete understanding of the present application, theobjects and advantages thereof, reference is now made to the followingdescriptions taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a diagram illustrating an embodiment of a stent according tothe present disclosure;

FIG. 2 is a diagram illustrating an end view of the stent illustrated inFIG. 1;

FIG. 3 is a diagram illustrating an end view of another embodiment of astent according to the present disclosure;

FIG. 4 is a diagram illustrating an end view of another embodiment of astent according to the present disclosure;

FIG. 5 is a diagram illustrating another embodiment of a stent accordingto the present disclosure;

FIG. 6 is a diagram illustrating another embodiment of a stent accordingto the present disclosure; and

FIG. 7 is a diagram illustrating an end view of the stent illustrated inFIG. 6.

DETAILED DESCRIPTION

FIG. 1 is a diagram illustrating an embodiment of a stent 10 inaccordance with the present disclosure. FIG. 1 illustrates stent 10 in afurled small-diameter state; it should be understood that stent 10 isexpandable to a large-diameter state (e.g., by balloon catheterinsertion and inflation/pressurization). Embodiments of stent 10according to the present disclosure include an element 20 disposed in acoiled manner and extending in a longitudinal direction to define alongitudinal axis 22 of stent 10. Element 20 is coiled in the directionof axis 22 to form a number of central lobes 24 (e.g., each rotation ofelement 20 forming one lobe 24). In some embodiments, lobes 24 areequally spaced along the longitudinal direction of stent 10 or have auniform coil pitch along stent 10 (i.e., a uniform distance between eachcoil). However, it should be understood that the coil pitch may varyalong one or more portions of stent 10.

In the embodiment illustrated in FIG. 1, stent 10 also includesperipheral lobes 28 formed on one or more central lobes 24. Lobes 28 areformed by additional coils of element 20 during a coil rotation of aparticular lobe 24. In the embodiment illustrated in FIG. 1, eachcentral lobe 24 includes three peripheral lobes 28. However, it shouldbe understood that the quantity of peripheral lobes 28 formed alongcentral lobes 24 may vary (e.g., a greater or fewer quantity). Further,in FIG. 1, each central lobe 24 includes peripheral lobes 28. However,it should be understood that some central lobes 24 may be devoid of aperipheral lobe 28, or some central lobes 24 may include a greater orfewer quantity of peripheral lobes 28 than other central lobes 24.

In some embodiments, stent 10 comprises longitudinal support rods 30extending in the axial direction of stent 10. For example, in theembodiment illustrated in FIG. 1, stent 10 comprises three support rods30; however, it should be understood that stent 10 may include a greateror fewer quantity of support rods 30. In some embodiments, rods 30 maybe located at substantially equal distances from each other as measuredabout a circumference or cylindrical plane formed by lobes 24. However,it should also be understood that rods 30 may be located at unequaldistances relative to each other.

In some embodiments, element 20 and/or rods 30 may comprise anonmetallic material, such as a polymer fiber or multiple polymerfibers. For example, in some embodiments, element 20 and/or rods 30 maybe formed from Poly-L-Lactic Acid (PLLA). However, it should beunderstood that other materials may be used to form element 20 and/orrods 30. Rods 30 may be attached or otherwise secured to lobes 24 usinga variety of different methods or materials. For example, in someembodiments, rods 30 may be attached to lobes 24 using a PLLA material(e.g., PLLA dissolved in chloroform) such that the PLLA mixture is usedto glue or weld rods 30 to lobes 24. In some embodiments, rods 30 may beultrasonically welded to lobes 24. Rods 30 may be attached or otherwisesecured to each successive lobe 24 along the longitudinal length ofstent 10 or may be intermittently attached to lobes 24 as rod 30 extendsalong stent 10 (e.g., every other lobe 24, every third lobe 24, or atother uniform or non-uniform spacing intervals). Further, in someembodiments, rods 30 may be attached and/or otherwise secured toexternal sides of lobes 24; however, it should be understood that rods30 may be attached and/or otherwise secured to internal sides of lobes24. For example, in some embodiments, rods 30 may be woven orintermittently transition from an external location to an internallocation of stent 10 relative to lobes 24 as rods 30 extend along thelongitudinal length of stent 10. For example, and not by way oflimitation, rod 30 may be secured to stent 10 by attaching rod 30 to anexterior surface of a first and second lobe 24, to an interior surfaceof the third lobe 24, to the exterior surface of the fourth and fifthlobes, etc. Thus, rods 30 may weave inwardly and outwardly betweeninterior and exterior areas of stent as rods 30 extend in thelongitudinal direction according to a uniform or non-uniform pattern.

In the embodiment illustrated in FIG. 1, stent 10 is formed as a dualopposing helical stent 10. For example, in the embodiment illustrated inFIG. 1, stent 10 is formed by member 20 having an end located and/orinitiating at proximal end 40 of stent 10 and forming successive coils(forming lobes 24 and lobes 28) as member 20 advances in the axialdirection 41 toward a distal end 42 of stent 10. At distal end 42 ofstent, member 20 returns and/or is coiled in a direction 43 towardproximal end 40 forming successive coils (forming lobes 24 and lobes 28)as member 20 advances in the axial direction 43 toward proximal end 40.In FIG. 1, member 20 is wound in the same rotational direction (i.e.,clockwise or counterclockwise) for forming coils in the directions 41and 43 (e.g., clockwise winding in the direction 41, followed byclockwise winding in the direction 43). In the embodiment illustrated inFIG. 1, member 20 comprises a continuous element such that coils in bothdirections 41 and 43 are formed from a continuous member 20. However, itshould be understood that in some embodiments, the coils formed indirection 41 may be formed from one or more members 20, where the coilsformed in direction 43 may be formed by one or more different members20.

FIG. 2 is a diagram illustrating an end view of stent 10 illustrated inFIG. 1. In the embodiment illustrated in FIG. 1, stent 10 comprisesthree rods 30 ₁₋₃ located at an equal spacing relative to each other. Inthe embodiment illustrated in FIG. 2, rod 301 is attached to an interiorsurface of lobe 24. Further, in the embodiment illustrated in FIG. 2,peripheral coils 28 extend radially inward and are located at equalcircumferential spacing relative to each other. Further, in theembodiment illustrated in FIG. 2, peripheral lobes 28 formed as member20 is coiled in opposing directions along stent 10 (e.g., extending fromend 40 to end 42, then from end 42 to end 40) are located atsubstantially the same positions.

FIG. 3 is a diagram illustrating an end view of another embodiment ofstent 10. In the embodiment illustrated in FIG. 3, stent 10 comprisesrods 30 ₄₋₉ attached to exterior sides of lobes 24. In FIG. 4, some ofrods 30 ₄₋₉ are located at unequal distances relative to each other asmeasured along the cylindrical plane formed by lobes 24. For example, inFIG. 3, a set of rods 30 ₄, 30 ₆ and 30 ₈ are located substantiallyequidistant from each other as measured along the cylindrical plane ofstent 10, and rods 30 ₅, 30 ₇ and 30 ₉ are located substantiallyequidistant from each other as measured along the cylindrical plane ofstent 10. However, each set of rods 30 are offset slightly from eachother such that the distance between rods 30 ₄ and 30 ₅, for example, isless than the distance between rods 30 ₄ and 30 ₉. Thus, it should beunderstood that the spacing of rods 30 on stent may vary.

FIG. 4 is a diagram illustrating an end view of another embodiment ofstent 10. In the embodiment illustrated in FIG. 4, peripheral lobes 28formed while member 20 is coiled in direction 41 are positioned atdifferent locations than lobes 28 formed as member 20 is coiled in thedirection 43. For example, referring to FIGS. 1 and 4, as member 20 iscoiled in direction 41, peripheral lobes 28 are formed at the positionsindicated in FIG. 4 by 28 ₁-28 ₃. As member 20 is coiled in thedirection 43 from end 42 toward end 40, peripheral lobes 28 are formedat the positions indicated in FIG. 4 by 28 ₄-28 ₆. Thus, in someembodiments, lobes 28 formed as member 20 is coiled in direction 41 maybe offset from the positions of lobes 28 formed as member 20 is coiledin direction 43. In FIG. 4, lobes 28 are illustrated having an equalspacing there between (e.g., corresponding to each coil direction).However, it should be understood that the spacing between lobes 28 mayvary (e.g., for each individual lobe 28 and/or between coil directions41 or 43).

In some embodiments, stent 10 is formed on a mandrel or other type ofcoil or winding tool to facilitate coiling of member 20 to form lobes 24and 28 and/or to facilitate attachment of rods 30. In some embodiments,while stent 10 is located on such tool or mandrel, stent 10 is annealedto enable shape retention of the stent as well as to align and/orotherwise form polymer chain orientation characteristics. For example,in a PLLA application, stent 10 may be annealed at a temperatureslightly above a glass transition temperature for a desired time period(e.g., 62° Celsius to 90° Celsius for approximately twenty-fiveminutes). Stent 10 may then be allowed to cool to room temperature forsome period of time (e.g., eighteen hours). However, it should beunderstood that the annealing process may be varied, especially fordifferent types of stent materials.

FIG. 5 is a diagram illustrating another embodiment of stent 10. In theembodiment illustrated in FIG. 5, stent 10 comprises lobes 24, lobes 28and rods 30. In FIG. 5, stent 10 is formed as a counter coil helicalstent 10. For example, in the embodiment illustrated in FIG. 5, stent 10is formed by member 20 having an end located and/or initiating atproximal end 40 of stent 10 and forming successive coils (forming lobes24 and lobes 28) as member 20 advances in direction 41 toward distal end42 of stent 10. At distal end 42 of stent, member 20 returns and/or iscoiled in direction 43 toward proximal end 40 forming successive coils(forming lobes 24 and lobes 28) as member 20 advances in the direction43 toward proximal end 40. In the embodiment illustrated in FIG. 5,member 20 is coiled or wound in one rotational direction for formingcoils as member 20 is moved in direction 41 and is coiled or wound in anopposite rotational direction for forming coils as member 20 is moved indirection 43 toward end 40. For example, in some embodiments, the coilsformed as member 20 is moved in direction 41 result from winding member20 in the direction indicated by 50 (i.e., clockwise). The coils formedas member 20 is moved in direction 43 result from winding member 20 inthe direction indicated by 52 (i.e., counterclockwise). As describedabove in connection with FIGS. 1-4, the spacing, quantity and locationsof lobes 28 and/or rods 30 may vary. In the embodiment illustrated inFIG. 5, member 20 comprises a continuous element such that coils in bothdirections 41 and 43 are formed from a continuous member 20. However, itshould be understood that in some embodiments, the coils formed indirection 41 may be formed from one or members 20, where the coilsformed in direction 43 may be formed by one or more different members20.

FIG. 6 is a diagram illustrating another embodiment of stent 10. In theembodiment illustrated in FIG. 6, stent 10 comprises lobes 24, lobes 28and rods 30. In FIG. 6, lobes 28 are formed to lie substantially in thecylindrical plane formed by lobes 24. For example, FIG. 7 is a diagramillustrating an end view of stent 10 illustrated in FIG. 6. Asillustrated in FIG. 7, peripheral lobes 28 are formed to lie and/orreside substantially in the cylindrical plane formed by lobes 24. In theembodiment illustrated in FIGS. 6 and 7, stent 10 includes three lobes28 per turn or coil (e.g., per lobe 24). However, the quantity and/orspacing of lobes 28 within a particular lobe 24 may vary. Further, thequantity, spacing and/or place of attachment of rods 30 (e.g., interiorsurface or exterior surface of lobes 24) may vary. As described above,stent 10 may be annealed to secure and/or otherwise maintain thepositioning of lobes 28 substantially within the cylindrical plane ofstent 10, thereby reducing the likelihood that lobes 28 would interfereand/or obstruct the insertion of a delivery catheter into the interiorarea of stent 10.

In the embodiment illustrated in FIG. 6, stent 10 also comprises abifurcated area or portion 60. For example, in some embodiments, stent10 may be formed such that the axial pitch between successive coils in amedial portion of stent 10 is increased, thereby resulting in a locationwhere another stent may be attached to and/or inserted through a wall ofstent 10. For example, in some embodiments, the bifurcated portion 60 isformed such that the axial pitch between successive coils is largeenough to accommodate a branch stent attachment to stent 10 and/orinsertion of another stent through portion 60 (e.g., into a branchingvessel). The medial location of portion 60 along stent 10 may vary(e.g., closer to end 40, closer to end 42, or anywhere in between). Itshould also be understood that bifurcated portion 60 may be included inthe embodiments of stent 10 illustrated and described in connection withFIGS. 1 and 5.

In some embodiments, peripheral lobes 28 are formed having a generallycircular form. However, it should be understood that the shape of lobes28 may vary (e.g., elliptical, rhomboidal, or other non-circular shape).Further, the size of lobes 24 and/or lobes 28 may vary.

In some embodiments, a radio-opaque material may be used in stent 10 toenable x-ray and/or fluoroscopic identification of stent 10 duringdelivery or deployment. For example, in some embodiments, bariumsulfate, water-soluble iodine and/or other materials may be laced orloaded into the polymer material used to form member 10 and/or rods 30.In some embodiments, a radio-opaque material may be used in combinationwith a PLLA material (e.g., PLLA dissolved in chloroform) such that thePLLA mixture having a radio-opaque material loaded therein is used toglue or weld rods 30 to lobes 24, thereby providing fluoroscopicvisibility of stent 10. In some embodiments, a radio-opaque material maybe attached to stent, such as securing a radio-opaque metal (e.g.,platinum) to rod(s) 30 and/or member 10. The radio-opaque material maybe attached using a PLLA material or other type of attachment mechanism.Further, in some embodiments, a radio-opaque sheath may be used withstent 10. For example, in some embodiments, a film comprised of a PLLAmaterial loaded with a radio-opaque material is wrapped partially orentirely around stent 10 to enable x-ray and/or fluoroscopicidentification of stent 10 during delivery or deployment.

Thus, embodiments of the present disclosure provide a flexible,expandable stent that enables increased ease and flexibility of deliveryand expansion. Further, embodiments of the present disclosure provide astent with excellent mechanical properties while providing plasticdeformation.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present disclosure has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the disclosure in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure. Theembodiment was chosen and described in order to best explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various embodiments with various modifications as are suited to theparticular use contemplated.

The invention claimed is:
 1. A non-metallic stent having a furledsmall-diameter state and an expanded large diameter state, the stentcomprising, in the furled small-diameter state: a first plurality ofcentral lobes arranged at spaced apart intervals and extendinglongitudinally defining a stent axis; a second plurality of centrallobes arranged at spaced apart intervals and extending longitudinallyalong the stent axis, wherein the first plurality of central lobes andthe second plurality of central lobes define a cylindrical surface ofthe stent; and at least one peripheral lobe formed on at least one ofthe first plurality of central lobes and on at least one of the secondplurality of central lobes, wherein the at least one peripheral lobe isoriented within the cylindrical surface and extends longitudinally alongthe stent axis; and wherein each lobe of the first plurality of centrallobes, the second plurality of central lobes, and the at least oneperipheral lobe formed by a coiled rotation of an element; and wherein,as the element is rotated in a rotational winding direction, the firstplurality of central lobes are formed in a first longitudinal directionalong said stent axis and the second plurality of central lobes areformed in a second longitudinal direction along said stent axis to formrespective first and second helices having an opposing winding patternalong the stent axis.
 2. The stent of claim 1, wherein the element isloaded with a chemical agent.
 3. The stent of claim 2, wherein thechemical agent is a radio-opaque agent.
 4. The stent of claim 1, furthercomprising at least one longitudinal rod attached to one or more sidesof the first plurality of central lobes and the second plurality ofcentral lobes.